Expressions with letters

Japanese school year: Elementary 6

What you learn

Students learn to represent unknown quantities and mathematical relationships generally using letters like x, and evaluate them by substituting numbers. This serves as the foundation for algebra and scientific formulas. Familiarity with equations using shapes and basic arithmetic operations will help you succeed here.

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Key points

This rule simplifies multiplication between variables. We omit the multiplication sign " $\times$ " and write the variables $a$ and $b$ in alphabetical order as $ab$ .

a \times b = ab

This rule shows how to express division as a fraction. The dividend $a$ is placed on top as the numerator, and the divisor $b$ ( $b \neq 0$ ) is placed on the bottom as the denominator.

a \div b = \frac{a}{b} \quad (b \neq 0)

This rule simplifies multiplying a variable by $1$ . When multiplying any variable $a$ by $1$ , omit the $1$ and simply write $a$ .

1 \times a = a

This rule uses exponents to write repeated multiplication of the same variable. Multiplying variable $a$ by itself is written as $a^2$ , placing a superscript $2$ at the top right.

a \times a = a^2

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Practice 1Coming soon