ESTIMATION PRACTICE · SET L01
Everyday, multiplied
Small, repeated quantities can add up to surprisingly large totals. This collection covers a lifetime of seconds, the grains in a bag of rice and a decade of walking. The assumptions are provided in the questions, so you can concentrate on choosing the right operations and keeping units consistent.
Three questions · Untimed solo practice · Calculator and scratch notes available
Answers and worked explanations appear after you submit each estimate. Replaying keeps your first completed score.
Questions and ways to approach them
QUESTION 1 · Time
How many seconds are there in an 80-year life? Assume 365 days in every year.
Answer in: seconds
Build a conversion chain from years to days, hours, minutes and seconds. Keep the factors separate until the last step. Follow the stated 365-day assumption instead of adding a leap-year correction.
QUESTION 2 · Everyday
How many grains of rice are in a 5 kg bag? Assume each grain weighs 0.025 grams.
Answer in: grains
Convert the bag mass and the mass of one grain to the same unit. Then decide whether you need to multiply or divide. A smaller grain mass should lead to a larger number of grains; use that relationship to check your operation.
QUESTION 3 · Everyday
At 8,000 steps a day, how many steps would you take in 10 years? Assume 365 days a year.
Answer in: steps
Find a total for one year, then extend it to the full period. Keep the daily rate distinct from the number of days. Check that you have included the ten-year factor exactly once.
Review the reasoning, then try again
A close answer is useful, but so is knowing where an estimate went wrong. After each reveal, compare your assumptions with the worked explanation. Look for a unit conversion, a repeated factor or an uncertain starting value before deciding what to change on a replay.
Each round scores the ratio of the larger number to the smaller. A perfect estimate is 1×. Your three-round score is the arithmetic average of those ratios, so a large miss can outweigh two close answers. Read the scoring rules and examples.