Using a calculator: powers, roots and brackets

The Maths Habit

Two calculators work out 3 + 5 × 2. One shows 16, the other shows 13. Which is right?

13: multiply before you add

Which part is worked out first?

  1. 18.9 ÷ (2.7 + 1.5)

    2.7 + 1.5

  2. 4 + 32

    32

  3. 2 × 5 − 1

    2 × 5

  4. 10 − 6 ÷ 2

    6 ÷ 2

Estimate first

3.22 + 4.5 About 14

Estimate first

√6.25 × 4 About 10

Cubed or tripled?

1.23 Cubed: 1.2 × 1.2 × 1.2 = 1.728

Work out 2.62 + 3.7

the keys, in order
2.6x2+3.7=
the display shows
10.46
Answer10.46

Work out 6 × √5.29

the keys, in order
6×√5.29=
the display shows
13.8
Answer13.8

Work out 2.62 + 3.7

the keys, in order
2.6x2+3.7=
the display shows
10.46
Answer10.46

Work out (3.6 + 5.4) ÷ 0.4

the keys, in order
(3.6+5.4)÷0.4=
the display shows
22.5
Answer22.5

Work out 2.62 + 3.7

the keys, in order
2.6x2+3.7=
the display shows
10.46
Answer10.46

Work out 4.8 + √12.25

the keys, in order
4.8+√12.25=
the display shows
8.3
Answer8.3

Work out 2.62 + 3.7

the keys, in order
2.6x2+3.7=
the display shows
10.46
Answer10.46

Work out 1.43 − 0.6

the keys, in order
1.4x3−0.6=
the display shows
2.144
Answer2.144

Work out 2.62 + 3.7

the keys, in order
2.6x2+3.7=
the display shows
10.46
Answer10.46

Work out 7.2 ÷ (5.1 − 3.5)

the keys, in order
7.2÷(5.1−3.5)=
the display shows
4.5
Answer4.5

Using a calculator: powers, roots and brackets worksheet, page 1

Answer sheet

  1. Tom wants 18.9 ÷ (2.7 + 1.5) but types 18.9 ÷ 2.7 + 1.5. What should his answer be?

    4.5

  2. Sam types 3 + 52 and Jo types (3 + 5)2. Whose answer is bigger, and by how much?

    Jo's, by 36

  1. Work out 4.32 − √10.24

    15.29

  2. Work out 23.4 ÷ (1.7 + 2.8)

    5.2

  3. Which is bigger, 2.53 or 3.52? By how much?

    2.53, by 3.375
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