
Unit 7: Numeracy skills
Approximating and Estimating
Estimates and approximations bring 2 major benefits:
- They enable you to check that the final answer is near to the figure that your estimate led you to expect. This is particularly valuable if you are unsure in the use of the keys on the calculator.
- They can provide you with a ‘short cut’, by showing plainly that you do not need to do all the calculations (for example, when comparing figures in tables).
Example 1
Calculate 51 / 73 of 300
steps:
- Approximate 51 / 73 to 50 / 75 (move to figures that make easily handled fractions)
- Simplify 50 / 75 to 2 / 3 (by dividing top and bottom by 25)
- Approximate answer is 2 / 3 × 300 which gives 200
- Calculator answer 209.59 (in fairly close range to 200, your approximated answer)
SMILE - Numeracy skills by Tom Frank, Eric Williams and Clare Wright, University of Birmingham Careers Centre adapted by Marion Kelt Glasgow Caledonian University is licensed under a Creative Commons Attribution 3.0 Unported License.