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Estimate magnitudes reasonably and find winning strategies by working backward.
Preview · progress not saved — Chapter 1 is free
Introduce checking logic against extreme numbers.
Imagine someone tells you they have exactly one million hairs on their head. Should you believe them?
At times, we don't know or need an exact count of things. A rough estimate is often sufficient for the purpose at hand. More importantly, estimating helps us figure out if a number we hear actually makes logical sense in the real world.
Pro tip: You don't need a calculator to spot a bad claim—just a quick mental estimate!
Evaluate an unrealistic claim using estimation.
Sheetal is in Grade 6 and says she has spent around 13,000 hours in school till date.
Do you agree with her?
Use simple estimation. Think about:
The goal is not to get an exact answer, but to check whether 13,000 hours is a reasonable estimate.
Choose a reasonable estimate for how many hours Sheetal spends in school each day.
Think about holidays, weekends, and vacations. Use a simple rounded estimate.
Multiply school hours per day by school days per year.
Sheetal is in Grade 6. Include Nursery, KG, and Grades 1 to 6.
Multiply hours per year by the number of years in school.
Compare your estimate with 13,000 hours and write your conclusion.
Rules for the increment game.
Have you ever played a numbers game where you can always win if you know the secret? Try this with a friend.
Rules for Game #1:
Think about it: Is it better to go first or second? Let's use a math trick to find out.