Round It. Estimate It. Check It.

Why do children find rounding confusing?

Many children learn rounding as a digit rule — “look at the next digit, 5 or more rounds up” — before they know what rounding is for. Then 347 becomes 400 “because the 7 rounds up”, 368 becomes 300 “because you chop the end off”, and nobody is sure what happens to 350.

Rounding is really a question about distance: which landmark is this number closest to? Once a child can see that on a number line, the digit rule makes sense — and so do estimates.

Landmarks first, rules second

• 347 lives between 300 and 400
• it is 47 away from 300 and 53 away from 400
• so 347 rounds to 300

Find the two landmarks. Check which is closer. Exactly halfway rounds up.

Read more in how to round numbers to the nearest 10, 100 and 1,000.

The halfway rule, made clear

What about 35, 350 or 4,500 — numbers exactly in the middle? The game teaches one clear convention and uses it everywhere: when a number is exactly halfway between two landmarks, it rounds up. Pip’s Midpoint Detector lights up only on the exact middle, so children see the difference between “nearly halfway” and “exactly halfway”.

Digi thinks. Pip invents. Your child helps them learn.

Digi, the thoughtful robot guide from Place Value Quest and Time Quest, explains the ideas. His best friend Pip — a bouncy yellow inventor — tries everything straight away and makes exactly the mistakes real children make. Your child checks Pip’s thinking on the number line and helps fix it, so they become a co-teacher, not just a student.

Estimate first, then check

Estimating isn’t a guess. Round each number to a convenient landmark, then calculate in your head: 347 + 586 is about 300 + 600 = 900. The exact answer, 933, is close — so it’s sensible. If an answer is far away from the estimate, it’s worth checking again. This is the habit that helps children check written calculations at school, including four-digit subtraction with exchanging.

Read more in how to estimate answers to check calculations.

Three worlds, ten lessons

1. Rounding Valley — The number line, the Tens Bubble-Blower and the Midpoint Mystery
2. Estimation City — Nearest 100, nearest 1,000 and sensible estimates
3. The Estimation Expedition — Real-life estimating, estimate first, Detective Digi and the Great Estimation Quest

Every lesson finishes with a Digi Check and unlocks a matching outfit for Digi and Pip — astronauts, pirates, wizards and more.

Start the adventure at the top of the page ↑

Part of the Digi family

Estimation Quest builds on place value: knowing what each digit is worth makes rounding to 10, 100 and 1,000 much easier.