• Broadfern@lemmy.world
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    22 hours ago

    For me personally, anything times 5 can be reached by halving the number, then multiplying that number by 10.

    Example: 66 x 5 = Y

    • (66/2) x (5x2) = Y

      • cancel out the division by creating equal multiplication in the other number

      • 66/2 = 33

      • 5x2 = 10

    • 33 x 10 = Y

    • 33 x 10 = 330

    • Y = 330