Find the least number which when decreased by two is exactly divisible by 18, 45, and 63
with photo explaination step by step
Answers
Answer:
This question is right up my alley. I've taught this method successfully and repeatedly. The number you are looking for is called the Least Common Multiple (LCM). To find it, first list out the prime factors of each number.
36: 2, 2, 3, 3
45: 3, 3, 5
63: 3, 3, 7
80: 2, 2, 2, 2, 5
The LCM will be that number whose prime factors include each prime factor above at their greatest number of occurences for any number.
LCM: 2, 2, 2, 2, 3, 3, 5, 7
Now multiply. I find it useful to reorder these numbers and multiply numbers in sequence which make the mental math work better, not harder
(2×5) ×(3×3) ×(2×2×2)×7
10 × 9 × 8 × 7
90 × 56. (or 10! - 6!)
5040 <--- That's your answer. I'm tired. u test it.
no number is there
Step-by-step explanation:
Because 45-2 = 43 and 43 is a prime number hence no number is divisible...