Billy Rubin

I barely use Twitter.

[Billy Rubin @immigrunt]

@H0H0v ...so 2/10 'divided by half' is just 4/10.

So now we're left with 5/12 x 4/10, so we just multiply across, and get 20/120 which is the same as 2/12 which is the same as 1/6.

[Billy Rubin @immigrunt]

@H0H0v Simplify the terms:

1/4 divided by 3/5. You can do this by converting the divisor into its reciprocal, then multiplying across.

1/4 x 5/3 = 5/12

2/10 divided by 1/2; you could do the same process, or just realize that anything 'divided by half' is the same as doubling it, so..

[Billy Rubin @immigrunt]

@H0H0v The answer is 1, and it's easy to know that if you know four things:

- Anything to the power of zero is 1

- 1 to the power of anything is 1

- The square root of 1 is 1

- Anything divided by (or 'over') 1 is itself

[Billy Rubin @immigrunt]

@howie_hua That's so cool!

[Howie Hua @howie_hua]

Can you mentally calculate 14×26? 35×45? 91×89? If not, see how difference of squares can help you.

[Billy Rubin @immigrunt]

@howie_hua I'd do 36x20 then 36x4 then add them.

36x20 is like 36x2, and just put a zero at the end, so 720.

36x4 is just 36 doubled twice. Double it one, get 72. Double it again, get 144.

Add by column. 800+60+4

=864

[Billy Rubin @immigrunt]

@howie_hua First I subtract 40, which gets me 38. Then I subtract 10 and add 1. 29.

[Billy Rubin @immigrunt]

@RHSTUDYZONE I would write this 2 different ways: as fraction, as decimal:

(5/100)^2
(1/20)^2
1/20 x 1/20
1/400

(0.05)^2
0.05 x 0.05
0.0025

1/400 = 0.0025 = 0.25%

[Billy Rubin @immigrunt]

@RHSTUDYZONE 2(2/2) / 2
2 x 1 / 2
2 / 2
1

[Billy Rubin @immigrunt]

@howie_hua The L shape is 4+2

The remainder is 1+3+3.

13.

[Billy Rubin @immigrunt]

@RHSTUDYZONE x = 5
y = 10
? = 50

[Billy Rubin @immigrunt]

@JubileeAidge @Angela_Watson @teachbk My students and their parents would disagree with you, but OK. I'd like to request that my child never has to be taught by someone as ignorant as you, though.

[Howie Hua @howie_hua]

What's the point of math class?

[Billy Rubin @immigrunt]

@mehrdadbas72335 It's C, 64.

2^4 = 16, so what we're really dealing with here is 16x4.

Which is 64.

[Billy Rubin @immigrunt]

@H0H0v C

[Billy Rubin @immigrunt]

@KandissTaylor @taylorswift13 Hail Satan!

[Billy Rubin @immigrunt]

@LEJPMath It's 12. You do multiplication and division in order from left to right.

[Billy Rubin @immigrunt]

@howie_hua 83-30 is 53

53-9 is 44

I find it easiest to subtract by column.

[Billy Rubin @immigrunt]

@LEJPMath B is equal to 5.

[Billy Rubin @immigrunt]

@howie_hua I start with 5,000, and then I subtract by column.

5,000 - 2,000 = 3,000

3,000 - 300 = 2,700

2,700 - 60 = 2,640

2,640 - 4 = 2,636