Quantitative Aptitude – Number Series – How many 3-digit numbers are there

Slot – 1 – Quantitative Aptitude – Number Series – How many 3-digit numbers are there

Q. How many 3-digit numbers are there, for which the product of their digits is more than 2 but less than 7?
Answer: 21

Solutions:
Let the 3-digit number be abc so possible values of a×b×c are 3,4,5 and 6.
If a×b×c=3,(a,b,c)=(1,1,3) ,total such numbers=3
If a×b×c=4,(a,b,c)=(1,1,4) or (1,2,2),total such numbers=6
If a×b×c=5,(a,b,c)=(1,1,5) ,total such numbers=3
If a×b×c=6,(a,b,c)=(1,1,6),(1,2,3) ,total such numbers=9
Thus total possible values of abc = 3+6+3+9 = 21

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