Find the missing number: 5, 10, 20, ?, 80

Practice Questions

Q1
Find the missing number: 5, 10, 20, ?, 80
  1. 30
  2. 40
  3. 50
  4. 60

Questions & Step-by-Step Solutions

Find the missing number: 5, 10, 20, ?, 80
  • Step 1: Look at the numbers in the sequence: 5, 10, 20, ?, 80.
  • Step 2: Notice how the first number (5) changes to the second number (10).
  • Step 3: To find out how 5 becomes 10, we can see that 5 is multiplied by 2 (5 * 2 = 10).
  • Step 4: Now, look at how 10 changes to 20. Again, 10 is multiplied by 2 (10 * 2 = 20).
  • Step 5: Next, we need to find the missing number after 20. We will multiply 20 by 2.
  • Step 6: Calculate 20 * 2, which equals 40.
  • Step 7: Now, check the next number after the missing number, which is 80. We can verify that 40 * 2 = 80.
  • Step 8: Therefore, the missing number is 40.
  • Pattern Recognition – Identifying the sequence in a series of numbers, often involving arithmetic or geometric operations.
  • Multiplication – Understanding how to apply multiplication consistently to find missing elements in a sequence.
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