Ask Question
15 September, 16:24

If a and b are distinct positive integers. the units digit of a2 is equal to the units digit of a, and the units digit of b2 is equal to the units digit of

b. if the units digit of a·b is equal to neither the units digit of a nor the units digit of b, then what is the units digit of a·b?

+4
Answers (1)
  1. 15 September, 18:25
    0
    The units digit of a squared number is equal to the units digit of that number only for digits 1 (1^2=1), 5 (5^2=25) and 6 (6^2=36). So a and b must end with 1, 5 or 6.

    Now let's try all the combinations of these:

    1*5=5, not good since 5 is already used.

    1*6=6, not good since 6 is already used.

    5*6 = 30, unit digit 0, not used!

    so a*b has units digit 0.
Know the Answer?
Not Sure About the Answer?
Get an answer to your question ✅ “If a and b are distinct positive integers. the units digit of a2 is equal to the units digit of a, and the units digit of b2 is equal to ...” in 📙 Mathematics if there is no answer or all answers are wrong, use a search bar and try to find the answer among similar questions.
Search for Other Answers