Which estimation method adds only the front digits of each addend to produce a rough total?

• A. Clustering Estimation
• B. Front-end estimation
• C. Compatible numbers
• D. GCF

Answer: (B)

Front-end estimation is a quick way to estimate a sum by using only the most significant digits of each addend. You look at the front digits, add those, and treat the rest as not affecting the rough total in a big way. For example, with 427 and 368, you take the hundreds digits 4 and 3 and add them to get 7, so you’d estimate about 700. If the numbers were two-digit, you’d use the tens digits instead, always keeping the same place value in the final estimate. This approach is helpful when you need a fast sense of scale or to check whether a more precise calculation is reasonable. It’s different from other estimation methods, like clustering (grouping numbers into nearby values before adding) or using compatible numbers (adjusting addends to make mental math easier), or from methods based on factoring, which aren’t about quick rough sums.