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Joined 3 months ago
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Cake day: July 8th, 2025

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  • Is that what they call Common Core? I’ve heard the term but didn’t know how it changed the method of teaching math.

    Common core showed multiple ways that were intended to increase the understanding of how math works. This was one of the ways that was presented which wasn’t how they taught it when I was a kid. There were at least two that I remember when my kiddo was doing common core:

    • Double one of the numbers and add or subtract the difference between them (7 is two less than 9, so 9x9 then subtract 2)
    • Take enough from the smaller number to reach 10 and add what is left (9+7 to 10+6)


  • Sigh. Decimals contribute to length. Length.

    Yeah, I’m probably missing what you are saying because I’m replying to what you are writing and the more you explain it the less sense it makes. Like there is nothing that I can think of involving decimals that increases in length. Maybe number of steps, but that is also true the more digits are involved and decimals only add one extra step.


  • Multiplying by 5: mult by 10 divide by 2

    A very similar concept for tipping about 20% is taking 1/10th of the bill by moving the decimal one to the left and doubling that. To make it even easier for me I just round to the nearest $10 amount first.

    Bill: $66.20 -> move left and round up = $7.00 and double to $14.00. The exact 20% amount is a little over $13 but I tend to round up because it is also faster to add whole dollars to the bill.