Excel formula guides, error fixes and finance walkthroughs, with practice sheets.https://www.excelstreak.com/blogenhttps://www.excelstreak.com/blog/div0-errorhttps://www.excelstreak.com/blog/div0-error#DIV/0! means a formula divided by zero or by an empty cell. Why it happens, averages of nothing included, and how to show a clean result, with a practice sheet.Wed, 11 Nov 2026 00:00:00 GMTErrors & fixeshttps://www.excelstreak.com/blog/excel-interview-data-cleaninghttps://www.excelstreak.com/blog/excel-interview-data-cleaningExtra spaces, names in the wrong order, numbers stored as text and dates that aren't dates: the cleaning task interviewers love, solved with formulas, and a sheet that grades yours.Wed, 11 Nov 2026 00:00:00 GMTInterview prephttps://www.excelstreak.com/blog/excel-interview-dynamic-arrayshttps://www.excelstreak.com/blog/excel-interview-dynamic-arraysList each customer once, A to Z, for the region someone picks, in one formula that updates itself. The dynamic-array answer interviewers look for, and a sheet that grades yours.Wed, 11 Nov 2026 00:00:00 GMTInterview prephttps://www.excelstreak.com/blog/excel-interview-loan-paymenthttps://www.excelstreak.com/blog/excel-interview-loan-paymentThe finance question in Excel interviews: a loan's monthly payment and its total interest, with the rate, period and sign traps explained, an NPV follow-up, and a sheet that grades yours.Wed, 11 Nov 2026 00:00:00 GMTInterview prephttps://www.excelstreak.com/blog/excel-interview-lookuphttps://www.excelstreak.com/blog/excel-interview-lookupThe lookup task almost every Excel interview includes: bring a value across from a second table. The answer interviewers want, why VLOOKUP fails here, and a sheet that grades yours.Wed, 11 Nov 2026 00:00:00 GMTInterview prephttps://www.excelstreak.com/blog/excel-interview-sumifshttps://www.excelstreak.com/blog/excel-interview-sumifsTurn a raw sales list into a summary by region and product, without a pivot table. The formula interviewers expect, the $ signs that make it copy, and a sheet that grades yours.Wed, 11 Nov 2026 00:00:00 GMTInterview prephttps://www.excelstreak.com/blog/excel-interview-working-dayshttps://www.excelstreak.com/blog/excel-interview-working-daysInvoices due at the end of next month, and the working days a client has to pay: the date task interviewers set, solved with EOMONTH and NETWORKDAYS, plus a sheet that grades yours.Wed, 11 Nov 2026 00:00:00 GMTInterview prephttps://www.excelstreak.com/blog/name-errorhttps://www.excelstreak.com/blog/name-error#NAME? means Excel doesn't recognise a word in your formula: a misspelt function, text without quotes, a missing colon. Find it and fix it, with a practice sheet.Wed, 11 Nov 2026 00:00:00 GMTErrors & fixeshttps://www.excelstreak.com/blog/num-errorhttps://www.excelstreak.com/blog/num-error#NUM! means a calculation has no valid answer: an IRR with no rate to find, a square root of a negative. Each cause and its fix, with a practice sheet.Wed, 11 Nov 2026 00:00:00 GMTErrors & fixeshttps://www.excelstreak.com/blog/ref-errorhttps://www.excelstreak.com/blog/ref-error#REF! means a formula points at a cell that isn't there: deleted, or past the edge of a range. The usual causes and fixes, with a practice sheet.Wed, 11 Nov 2026 00:00:00 GMTErrors & fixeshttps://www.excelstreak.com/blog/value-errorhttps://www.excelstreak.com/blog/value-error#VALUE! means a formula got the wrong kind of value, most often text where it needs a number. The usual causes and fixes, with a practice sheet.Wed, 11 Nov 2026 00:00:00 GMTErrors & fixeshttps://www.excelstreak.com/blog/na-errorhttps://www.excelstreak.com/blog/na-error#N/A means a lookup didn't find what it was looking for. Here are the six usual causes, how to spot each one on the sheet, and the fix, with a practice sheet.Mon, 09 Nov 2026 00:00:00 GMTErrors & fixeshttps://www.excelstreak.com/blog/npv-in-excelhttps://www.excelstreak.com/blog/npv-in-excelExcel's NPV discounts the first number you give it. If that number is today's investment, your answer is wrong. Here's the fix, worked through, and a sheet that grades yours.Mon, 09 Nov 2026 00:00:00 GMTFinance & modellinghttps://www.excelstreak.com/blog/spill-errorhttps://www.excelstreak.com/blog/spill-error#SPILL! means a formula's result needs more cells than are free. Here's how to find what's in the way, the other causes of #SPILL!, and how to fix each one.Mon, 09 Nov 2026 00:00:00 GMTErrors & fixeshttps://www.excelstreak.com/blog/xlookup-vs-vlookuphttps://www.excelstreak.com/blog/xlookup-vs-vlookupXLOOKUP does everything VLOOKUP does with fewer ways to go wrong. Here's the same lookup written both ways, the five differences that matter, and when VLOOKUP is still the right call.Mon, 09 Nov 2026 00:00:00 GMTModern Excel