Kavi, the KAVI owl, waving on a book
HomeAcademyAIWho it's forPricingFAQLabsContactGet Started
Math · Stage 1

Fast mental maths: 2-digit numbers, tens first

Add and subtract 2-digit numbers in my head tens first, and double or triple small 2-digit numbers by splitting tens and ones..

✦ Math📘 Stage 1 · S1⏱ ~9 min🧒 Ages 5–6★ Free to start
add and subtract 2-digit numbers in my head tens first, and double or triple small 2-digit numbers by splitting tens and ones.
Start the free lesson →⬇ Printable PDF
Kavi the owl for Math
📖

Ayu and the rambutans

At the market, Ayu picks 34 rambutans. Her friend Budi picks 25. Their mother asks, how many altogether? Ayu has no paper and no pencil. She smiles, because she knows a quick way. She breaks each number into tens and ones. Her answer comes in a blink. Can you do that too? By the end I can add and subtract 2-digit numbers in my head, and double or triple small ones.

🎓

What your child will learn

1Wake up your number brain
2Two helper words
3Add tens first, then ones
4Jump to a tens number and adjust
5Take away tens first, then ones
6Jump back and give 1 back
7Double and triple by splitting
8Why splitting works
9Swap, split and cross a ten
10Pick a strategy
11Split way and written way
12Swap law and split law
13Build 24 three times
14Spot the mistake
15Check your thinking
16What I can do now
🔍

A peek inside

Ayu picks 34 rambutans and Budi picks 25. How many altogether, tens first?
Split: 34 = 30 + 4 and 25 = 20 + 5<br>Tens: 30 + 20 = 50<br>Ones: 4 + 5 = 9<br>Together: 50 + 9 = 59

Try this at home: Ayu picks 34 rambutans and Budi picks 25. How many altogether, tens first?

Ready to play and learn?

Start the free interactive lesson, or print the handout for screen-free play.

Start the free lesson →⬇ Download PDF

Part of Math · Stage 1 · S1 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.