Answer:
Step-by-step explanation:
I'm not sure my way is going to be any quicker or better. Let's take an example.
Suppose you start with 456
Put a decimal at the end of the 6. You get 456.
Shift the decimal to the left one place 45.6
Divide by 2
22.8 (done mentally)
Note: dividing by 2 is easier than dividing by 5. Or multiplying by 5 for that matter.
Check the result.
456 * 5/100 =2280 / 100.
Shift a decimal 2 places to the left.
22.80 which agrees with your result.
Answer: x= 207.8873386
Step-by-step explanation:
expecting both 2x-15 and 3x are angles in radiant, let's draw a rhombus ABCD
∠ABC = 2x-15
∠ BCD = 3x
∠ABC + < BCD= π ( 180° in radiant)
2x - 15 + 3x = π
5x - 15 = π
x - 3 = 1/5π
= 3.628318531 = 207.8873386
2x−15°+3x=180
5x-15°=180
5x=195°
x=39°
Answer:
Step-by-step explanation:
Find the amount of time it takes for a beam of light from the Sun to reach Earth.
<span>1. 5564÷91
I know that 9 * 6 = 56
5564 rounds to 5600
91 rounds to 9
Since 56/9 = 6, then 5600/90 is the same as 560/9 = 60
The estimate is 60
2. </span><span>5391÷25
5391 sounds to 5400
25 is 1/4 of 100.
That means when you divide by 25, you can divide by 100 and multiply by 4.
5400/100 = 54
54 * 4 = 216
Estimate: 216
3. </span><span>explain how to estimate 498÷12
48/12 = 4
498 is little more than 480, so 498/12 is little more than 40
4. </span><span>which is the closest estimate for 2130÷ 33
A.7 B.17 C.70 D.700
2130/33
Round off the numerator and denominator to
2100/30
Reduce the fraction
210/3
Since I know that 21/3 = 7, then 210/3 = 70
Estimate: 70
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