A phrase that has a value

The idea

Phrases combining numbers with operations such as +, –, × and ÷ are arithmetic expressions; every arithmetic expression has a value, the number it evaluates to, and the sign '=' links an expression to its value.

Mallika’s lunch

Mallika spends ₹25 every day on lunch at school. Today is Monday. She wants a phrase for what she spends from Monday to Friday.

Which phrase tells her total for the 5 days?

• 5 + 25
• 5 × 25
• 25 − 5

Build the phrase

Each story needs a phrase. Tap two number tiles and one operation tile to build it, and the machine tells you its value.

Phrase and value

You built 13 + 2, 20 − 4, 12 × 5 and 18 ÷ 3. Each is a phrase made of numbers and operations. Each works out to one number.

A phrase of numbers with +, −, × or ÷ is an arithmetic expression. Every expression has a value, the number it evaluates to. The sign = links an expression to its value: 13 + 2 = 15.

• Expression | How we read it | Value
• 13 + 2 | 13 plus 2, or the sum of 13 and 2 | 15
• 5 × 25 | 5 times 25, or the product of 5 and 25 | 125
• 20 − 4 | 20 minus 4 | 16
• 18 ÷ 3 | 18 divided by 3 | 6

Notes

An arithmetic expression is a phrase of numbers with +, −, × or ÷. It has a value, the number it evaluates to. The sign = links an expression to its value.

Check yourself

What is the value of the expression 12 × 5?

Answer: 60

12 × 5 = 60. The value of the expression is 60.

The expression for Mallika’s week is 5 × 25. How do we read it?

Mallika’s total for the week is the value of 5 × 25. How many rupees is that?

Answer: 125 ₹

5 × 25 = 125. Mallika spends ₹125 in the week.

• 5 plus 25, or the sum of 5 and 25. A sum is what we get by adding. The sign here is ×.
• 25 divided by 5. The sign here is ×, not ÷.
• 5 times 25, or the product of 5 and 25 — correct. Yes! A product is what we get by multiplying.