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Rounding and estimation
Rounding and estimation

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Activity 21

Without using your calculator solve the following calculations.

  • (a) 3 + 5 × 2 = ?

  • (b) 12 − 6 + 6 = ?

  • (c) 6 + (5 + 4) × 3 = ?

  • (d) (3 + 5) ÷ 2 = ?

  • (e) 12 − (6 + 6) = ?

  • (f) 6 + 5 + 4 × 3 ÷ 2 = ?

Check your answers using a scientific calculator.

Answer

  • (a) 5 × 2 = 10

  •      3 + 10 = 13.

  • (b) 12 − 6 = 6

  •      6 + 6 = 12.

  •      Remember that addition and subtraction belong to the same group and so the calculation is done from left to right.

  • (c) 6 + (5 + 4) × 3 = 6 + 9 × 3

  •      9 × 3 = 27

  •      6 + 27 = 33.

  • (d) (3 + 5) ÷ 2

  •      8 ÷ 2 = 4.

  • (e) 12 − (6 + 6) = 12 − 12 = 0.

  • (f) 6 + 5 + 4 × 3 ÷ 2 = 6 + 5 + 6 = 17.