Clever Computations
Find the value of x (hint: undoing): −5x+(2x−7)−(−3)=−4x+9
-3x-4=-4x+9
-3x+4x-4=9
x=13
−2(5y−3)+(−4y+6)
-10y+6-4y+6=-14y+12
Round 9,885,659,260 to the billions
10,000,000,000
What is the reciprocal of −7/3?
-3/7
What is the rule for adding numbers with different signs?
Subtract the smaller number from the greater number and keep the sign of your bigger number.
4−8+12−16+20−24+28−32+36−40+44−48
-24
(-25)((-2)(-16) - (-6)(3))
1,250
Round 0.99672 to the hundredths
1.00
Find the reciprocal of 11 and 7/12.
12/139
Write the equation and solve it. The product of y and 7 is negative 28. What is y?
7y = -28; so y = -4
4(599)-6(399)+3(799)+398
4x(600-1)-6x(400-1)+3x(800-1)+400-2=2400-4-2400+6+2400-3+400-2=2800-3=2797
−8+(3×(−2))−(−5)+12÷(−4)
-12
Round 1.495485 to the thousandths
1.495
Given 4/25×5/36, what is the simplest form of the reciprocal of the product?
45
Gary wanted to compute 200 ÷ 10 ÷ 2, and his reasoning was: “Well, 10 ÷ 2 is 5, so 200 ÷ 10 ÷ 2 is the same as 200 ÷ 5, which is 40, so the answer is 40.” Is Gary correct? Why or why not?
No. Division is not associative.
Joe adds up all the even integers from 2 to 202. Kate adds up all the integers from 1 to 101. What is Joe’s sum divided by Kate’s sum?
2
−3(4−2x) + 12−(6x+8)
-8
Round 1.7354958 to the hundred-thousandths
1.73550
What is the reciprocal of 2/3 to the power of 5?
729/32
If n=2 to the power of 10 plus 2 to the power of 11 plus 2 to the power of 12, what is the value of n divided by 2 to the power of 10?
The number 222,222 is equal to the product 37,037·6. What is the product of 37,037 and 27?
222,222 divided by 2 equals 37,037·3 = 111,111. So 37,037·27 = 37,037·3·9 = 111,111·9 = 999,999
−7a+2(3a−4)+(−5)÷1/a
-7a+6a-8-5a=-6a-8
Round the sum of 101.296794 and 55.19717 to the tenths
101.3+55.2=156.5
625
Simplify (a-(b-c)-d) - ((a-b)-c-d) - (a-(b-c)-d)
a-b+c-d-a+b+c+d-a+b-c+d=-a+b+c+d