Lesson eLearning

What is the sum of all even numbers between 10 and 20 inclusive?

hard 4 marks Class 1 · Mathematics · Numbers from Ten to Twenty
Answer
90

The correct answer is 90 — Sum is 90.

Step-by-step solution

  1. List the even numbers between 10 and 20: 10, 12, 14, 16, 18, 20.
  2. Add them one by one: 10 + 12 = 22.
  3. Add next number: 22 + 14 = 36.
  4. Add next: 36 + 16 = 52.
  5. Add next: 52 + 18 = 70.
  6. Add last: 70 + 20 = 90.
  7. Sum is 90.
Common mistake: Including odd numbers or forgetting the 20 in the sum

Concept tested: Summing a subset of numbers

Published · How this solution was prepared and checked

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