Arithmetic operations (+−×÷)

Enumerating sets

Number bonds - Decomposition

Meaning of operations

Number bonds

Quiz: Number bonds

Tables of addition and subtraction

Multiples and prime numbers

Multiplication and division tables

Let's review our arithmetic tables

Calculator

Consul, the Educated Monkey

Double pan balance

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Abacus (suanpan)

Abacus (soroban)

Pascaline