# Math Is Fun Forum

Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

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## #2 Re: Introductions » New Member From NYC » 2021-03-29 08:13:47

Hello mathland
It is great to see another old guy as I have just turned 50 myself

## #10 Re: Ganesh's Puzzles » Oral puzzles » 2021-03-29 03:48:20

#4975

The number of digits in the square root of a number with an even number digits is n/2 and (n+1)/2 for numbers with an odd number of digits. But this rule applies to perfect squares. However 62478078 is not a perfect square and thus its square root has an infinite number of digits in it’s decimal.

## #19 Re: This is Cool » Multiplying Large Numbers in your head » 2021-03-27 05:33:35

Interesting. I think many people have trouble calculating products in their head because of the way we were taught to do it by hand from right to left which isn’t really our customary way of thinking. Because of this teaching style and the way we think multiplying 72x11 may seem awkward. We are taught to multiply 1x72 then add 1x72 and shift it to the left. This isn’t really natural. At least for me it is much more natural to multiply 10x72 and add 1x72. It just feels natural and simple to add 720+72=792 in my head rather than 72+720. Or maybe I am just strange