Math · Stage 4
Build numbers from digit clues (parity, digit sum, fixed digit)
A clue pins the answer: parity fixes the last digit, a digit sum fixes what the digits add to, and a fixed-digit clue locks one digit to one place.
✦ Math📘 Stage 4 · S4⏱ ~11 min🧒 Ages 8–9★ Free to start
I can build numbers from digit clues (parity, digit sum, fixed digit).
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Kavi's Mystery Number 🔍
Kavi has three digit cards — 5, 2 and 8 🔢 — and a clue: “the number is even.” “Even means it must end in an even digit,” hoots Kavi, “so I can end in 2 or 8. To make it the biggest, I keep the big digits in front → 852!” One little clue, and the mystery number falls out.
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What your child will learn
1A fixed digit locks one placeEach digit is worth more the bigger its place. In 846 the 8 is worth 8 hundreds, the 4 is 4 tens, the 6 is 6 ones. A fixed-digit clue like “the 4 must stay in the tens place” locks that place — you only arrange the other digits.
2Place the digits to obey the clueBuild the largest number from the cards 8, 4, 6 with the clue “4 must stay in the tens place”. The 4 is locked — so put the bigger of the other two in the hundreds. Drop each card in the right box →
3Even or odd? Look at the last digitA parity clue (“make it even” or “make it odd”) only cares about the last digit. Even numbers end in 0, 2, 4, 6, 8; odd numbers end in 1, 3, 5, 7, 9. Tap each card to compare.
4Add the digits for the digit sumA digit-sum clue adds all the digits together. For 528, add the three digits one at a time — each bar is one digit. The total height is the digit sum.
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A peek inside
Build the largest 3-digit number from 4, 1, 6 with the 1 fixed in the tens place.
1 is locked in tens → _ 1 _; put the bigger free digit 6 in the hundreds, 4 in the ones
Try this at home: Fixed digit: largest number from 2, 9, 4 with the 4 in the tens place = __
Ready to play and learn?
Start the free interactive lesson, or print the handout for screen-free play.
Part of Math · Stage 4 · S4 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.