O Construtor de Formulas do Excel: Transforme um Calculo em Portugues Simples em uma Formula Funcional
Porque é que este prompt importa
Hand-built spreadsheet formulas for board and finance decks fail quietly far more often than people expect. A SUM that drops a text-formatted cell, an AVERAGE that includes a header row, or a blank cell silently treated as zero can shift a reported KPI enough to trigger a strategic conversation based on a wrong number. Once a bad figure has been presented to finance or the board, correcting it afterward costs far more in credibility than the two minutes it takes to get the formula right and understand exactly why it works before you present it.
Para que o usamos
You're a sales operations analyst at a mid-size SaaS company, working in a Google Sheets pipeline tracker with roughly 3,000 rows. Finance needs the weighted average discount percentage across all deals marked "Closed Won" in Q3, weighted by deal value, and a few rows have a blank discount field because a rep forgot to fill it in. The number is due in the quarterly business review deck in two hours, and you need a formula that handles the blanks correctly instead of silently including them as zero and skewing the average down.
Prompt
Act as a senior data analyst who has spent years cleaning up broken finance and sales spreadsheets and knows exactly how formulas silently fail. Context: I need a formula for the following calculation, described in plain English: [DESCRIBE THE CALCULATION YOU NEED, e.g. "weighted average discount percentage for all deals marked Closed Won, weighted by deal value"] Tool: [SPECIFY Excel (and version, e.g. Excel 365) OR Google Sheets] Relevant data: [DESCRIBE YOUR COLUMNS/RANGES OR PASTE A SAMPLE ROW, e.g. "Column G = deal stage, Column H = close date, Column I = discount %, Column J = deal value, data starts row 2, ends row 3000"] Edge cases to handle: [LIST ANYTHING THAT COULD BREAK A NAIVE FORMULA, e.g. "some rows in the discount column are blank," "some deal values are stored as text," "I only want deals closed within a specific date range"] Task: 1. Write the working formula, ready to copy and paste directly into the cell. 2. Break down what each part of the formula does, in plain English, step by step. 3. Flag anything in my data description that is likely to break this formula (mismatched data types, absolute vs. relative references, off-by-one range errors). 4. If the tool I specified has a simpler function available in a recent version that could replace an older-style formula, mention it as an alternative. 5. If there's a meaningful syntax difference between Excel and Google Sheets for this formula, note it even if I only asked about one. Constraints: Avoid volatile functions (OFFSET, INDIRECT, NOW, TODAY) unless the calculation specifically requires them. The formula must be copy-paste-ready with no placeholder text left inside it — resolve every range and condition using the data description I gave you. Assume I am an intermediate spreadsheet user: I understand basic functions like SUM and IF but don't regularly write nested array formulas. Output Format: - The Formula (in a code block, copy-paste ready) - Step-by-Step Breakdown (numbered, plain English) - What Could Break It (bulleted) - Excel vs. Google Sheets Note (only if relevant) - Simpler Alternative (only if one exists)
Resultado
The Formula (Google Sheets, weighted average discount for Closed Won deals in Q3, ignoring blank discount rows):
=SUMPRODUCT((G2:G3000="Closed Won")*(H2:H3000>=DATE(2026,7,1))*(H2:H3000<=DATE(2026,9,30))*(I2:I3000<>"")*I2:I3000*J2:J3000)/SUMPRODUCT((G2:G3000="Closed Won")*(H2:H3000>=DATE(2026,7,1))*(H2:H3000<=DATE(2026,9,30))*(I2:I3000<>"")*J2:J3000)Step-by-Step Breakdown
- The formula is built from two SUMPRODUCT calls: the top one calculates the sum of (discount × deal value) for qualifying rows, and the bottom one calculates the sum of deal value alone for the same rows. Dividing the first by the second gives a value-weighted average rather than a simple average.
- Each condition inside the parentheses — (G2:G3000="Closed Won"), the date range check, and (I2:I3000<>"") — evaluates to TRUE (1) or FALSE (0) for every row. Multiplying these conditions together means a row only contributes to the total if ALL conditions are true simultaneously.
- The (I2:I3000<>"") condition is what solves your blank-discount problem: any row where the discount cell is empty evaluates to FALSE, zeroing out that row's contribution entirely instead of treating a blank as a 0% discount, which would have dragged your average down incorrectly.
- The date range conditions (H2:H3000>=DATE(2026,7,1)) and (H2:H3000<=DATE(2026,9,30)) restrict the calculation to close dates within Q3 2026 specifically.
What Could Break It
- If the discount column (I) is formatted as text instead of a number (common when values are pasted from another system with a % sign as text), SUMPRODUCT will treat those cells as zero rather than throwing an error — check for left-aligned numbers in that column, which usually signals text formatting.
- If deal value (Column J) contains any blank or text cells within qualifying rows, the multiplication will silently zero out that row's contribution to both sums, which is usually fine but worth confirming isn't hiding missing data.
- The range G2:G3000 assumes your data never exceeds row 3000 — if new deals get added below that row, this formula will silently exclude them. Consider converting your range to a Table (Ctrl+T in Excel, or an equivalent structured range in Sheets) so the formula auto-expands.
Excel vs. Google Sheets Note: This exact formula works identically in Excel 365 and Google Sheets — SUMPRODUCT syntax is consistent across both. In older Excel versions (pre-2007), you may need to enter it as an array formula with Ctrl+Shift+Enter, but modern Excel and Sheets both evaluate it as a normal formula.
Simpler Alternative: If you only needed a straight sum-based condition without the weighting, SUMIFS would be simpler and faster to read — but because this calculation requires weighting by deal value, SUMPRODUCT is the correct tool here rather than a simplification.
A maioria das pessoas que precisa de uma formula de planilha na verdade nao quer aprender a sintaxe de planilhas — quer o numero correto na celula, uma explicacao em que possa confiar, e a garantia de que nao vai quebrar silenciosamente na proxima vez que alguem adicionar uma linha. Este prompt foi construido para entregar exatamente isso, e sua estrutura foi deliberadamente projetada em torno dos pontos onde os pedidos de formulas geralmente falham.
Por que este prompt e estruturado dessa forma
O enquadramento do Papel — um analista de dados senior que passou anos consertando planilhas financeiras e de vendas quebradas — importa porque direciona o modelo para uma escrita de formula defensiva em vez da resposta tecnicamente correta mais curta. Um modelo simplesmente questionado escreva uma formula para X frequentemente devolvera algo que funciona em dados limpos e quebra no momento em que uma celula em branco ou um numero formatado como texto aparece. Enquadrar o modelo como alguem que ja depurou pessoalmente essas falhas faz com que ele as sinalize proativamente em vez de esperar ser perguntado.
A secao de Contexto separa explicitamente a descricao do calculo, a ferramenta (Excel ou Sheets), o layout dos dados e os casos extremos em quatro entradas distintas em vez de um unico paragrafo. Isso importa porque os pedidos de formula falham com mais frequencia quando um desses elementos esta faltando — alguem descreve o calculo claramente mas esquece de mencionar um caso extremo de celula em branco, e recebe de volta uma formula que esta correta em teoria mas errada em seus dados reais.
A lista de cinco tarefas termina deliberadamente com um pedido de uma alternativa mais simples e uma nota de sintaxe entre ferramentas. Analistas frequentemente nao sabem que uma funcao que estao usando foi substituida por algo mais limpo em uma versao recente, ou que a formula que estao prestes a colar no Google Sheets usa sintaxe exclusiva do Excel. Pedir ambos antecipadamente detecta isso antes que se torne um erro de copiar e colar descoberto no meio de uma apresentacao.
Como adaptar
Para um calculo muito mais simples — uma SOMA direta ou um CONT.SE sem complexidade de ponderacao ou tratamento de celulas em branco — o modelo devolvera corretamente uma funcao curta em vez de fabricar complexidade desnecessaria com SOMARPRODUTO ou formulas de matriz. A estrutura se ajusta tanto para baixo quanto para cima.
Para calculos recorrentes que sua equipe executa em cada ciclo de relatorios, vale a pena salvar a formula final junto com sua explicacao passo a passo em algum lugar que toda a sua equipe possa consultar — isso transforma um prompt pontual em conhecimento institucional que sobrevive mesmo quando o analista original muda para outro projeto.