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knight247
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1. How many three digit numbers 'n' are there which are divisible by 9 so that both n and n^2 have the same units digit?
a.20
b.21
c.22
d.23
e.24
I figured out the number of 3 digit multiples of 9 using the formula
Total=(Biggest-Smallest)/Increment+1=(999-108)/9+1=100
Also figured out that for n and n^2 to have the same units digit the numbers would have to end in 5 or 6 eg 36, 45 etc....Just not able to move ahead from here. Detailed explanations would be appreciated
2. How many three digit numbers 'n' are there which are divisible by 9 so that both n and n^2 leave the same remainer when divided by 10?
a.20
b.21
c.22
d.23
e.24
I know that whenever a non-multiple of 10 is divided by 10 the remainder is always the units digit.
Once u figure that out...Its the same as the previous problem.
a.20
b.21
c.22
d.23
e.24
I figured out the number of 3 digit multiples of 9 using the formula
Total=(Biggest-Smallest)/Increment+1=(999-108)/9+1=100
Also figured out that for n and n^2 to have the same units digit the numbers would have to end in 5 or 6 eg 36, 45 etc....Just not able to move ahead from here. Detailed explanations would be appreciated
2. How many three digit numbers 'n' are there which are divisible by 9 so that both n and n^2 leave the same remainer when divided by 10?
a.20
b.21
c.22
d.23
e.24
I know that whenever a non-multiple of 10 is divided by 10 the remainder is always the units digit.
Once u figure that out...Its the same as the previous problem.
