various elementary math?

Question

LCM of 50 and 60?

estimate
7/8 +3 1/4=

estimate

5 1/9 - 2/3=

Answer 1

50 and 60 have a common factor of 10, so the LCM is
(50*60) / 10 = 300

7/8 is close to 1
3 1/4 is close to 3
1+3 = 4

5 1/9 is close to 5
2/3 is close to 1
5 - 1 = 4

Answer 2

LCM of 50 and 60:
50—60: 2
25—30: 5
5—6

2 * 5 * 5 * 6 = 300

Answer: 300

7/8 + 3 1/4 = 7/8 + 13/4 = 7/8 + 26/8 = 33/8 or 4 1/8

Answer: 4 1/8

5 1/9 - 2/3 = 46/9 - 2/3 = 46/9 - 6/9 = 40/9 or 4 4/9

Answer: 4 4/9

Answer 3

Ok,

The LCM of 50 and 60 is 300 because it is the smallest number that both 50 and 60 can go into. I figured this out by realizing that a multiple of 50 would have to be an even hundred number (i.e. 100, 200, 300...) and 60 does not go into 100 or 200 evenly, so we are left with 300!

next estimate

7/8 is close to 1 rounded up

and

3 1/4 is close to 3 rounded down

therefore...

1 + 3 = 4

next estimate

5 1/9 is close to 5 rounded down

and

2/3 is close to 3 rounded up

therefore

5 - 3 = 2

Hope this helps!

Answer 4

LCM of 50 and 60? The smallest non-zero number that is a multiple of both:
50 = 50, 100, 150, 200, 250, 300, 350
60 = 60, 120, 180, 240, 300
300 is LCM

Estimate --> Get a common denominator on bottom, then add:
7/8 +3 1/4
=7/8 + 13/4
= 7/8 + 26/8
= 33/8 (which is the same as: 4 1/8)
= 4 (whole number it is closest to rounding down)

Estimate -->get common denominator on bottom, then add
5 1/9 - 2/3
= 46/9 - 2/3
= 46/9 - 6/9
= 40/9 (which is the same as: 4 4/9)
= 4 (whole number it is closest to rounding down)

Answer 5

60 120 180 240 300
50 100 150 200 250 300
LCM = 300

7/8 + 26/8 = 33/8 = 4 1/8

46 / 9 - 6 / 9 = 40 / 9 = 4 4/9

Answer 6

for LCM, list the prime factors of each:
50= 2*5*5
60=2*2*3*5
Circle any number that appears in both lists: you circle one pair of 2s and one pair of 5s. Multiply all the factors, but only once for each circled pair. 2*2*3*5*5 = 300

Answer 7

For LCM you've gotta list the prime factors of each