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Numbers, units and arithmetic
Numbers, units and arithmetic

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3.1 Arithmetic with whole numbers

When you are adding or subtracting whole numbers, an important thing to keep in mind is the place value of the figures. It is often a good idea to set out the numbers in columns before doing the arithmetic.

Example 11

  • (a) There are 4985 people living in a village and 93 people living in a nearby hamlet. How many people live in the village and the hamlet in total?

  • (b) Of the total number of people in the village and hamlet, 1352 are under voting age. How many people are eligible to vote?


  • (a) There are 5078 people altogether.

    multiline equation line 1 4985 line 2 plus 93 line 3 5078
  • An alternative method is to note that 93 is 7 less than 100. So add 100 to 4985 (5085) and subtract 7 (5078).

  • (b) 3726 people are eligible to vote.

    multiline equation line 1 5078 line 2 minus 1352 line 3 3726