Math · Stage 6
Number bases (read and convert base 2 and 5)
The same string of digits means different amounts in a different base. Multiply each digit by its place value and add — that reads a number in any base.
✦ Math📘 Stage 6 · S6⏱ ~14 min🧒 Ages 10–12★ Free to start
I can read and convert numbers in other bases.
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Kavi Cracks the Code 🦉
Kavi found a secret note that read just 1 0 1 1 🔎. “In our everyday numbers each place is ten times the one beside it,” said Kavi. “But a base tells you the jump. In base two the places double — 8, 4, 2, 1 — so 1011 means 8 + 0 + 2 + 1 = 11. In base five the places go ×5 — 25, 5, 1. Same digits, different base, different amount!”
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What your child will learn
1In base two, every place DOUBLESOur ordinary numbers use base ten: each place is ten times the next (1, 10, 100…). Base two uses only the digits 0 and 1, and each place is just twice the one on its right.
2The base tells you the place valuesTap each card. The digits 1 0 1 look the same, but the base decides what each place is worth.
3In base five, every place is ×5Base five uses the digits 0, 1, 2, 3, 4 — never a 5 or more. Each place is five times the one on its right: ones, fives, twenty-fives…
4Could this be a base-five number?A base-five number can only use the digits 0, 1, 2, 3, 4. If you spot a digit 5, 6, 7, 8 or 9, it cannot be base five. Sort each one →
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A peek inside
Read the base-two number 1011 in base ten. (places are 8, 4, 2, 1)
multiply each digit by its place value and add: 1×8 + 0×4 + 1×2 + 1×1 = 8 + 0 + 2 + 1
Try this at home: Read in base ten: base-two <b>1100</b> → __
Ready to play and learn?
Start the free interactive lesson, or print the handout for screen-free play.
Part of Math · Stage 6 · S6 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.