There is no such number.
The first squared number that is a multiple of 10 is three digits.
20
The number is 490.
I have two digits.I am between 16 and 24.I am one-quarter of a multiple of ten
77
63
630
If it's to be a multiple of 9 the its digits must sum to a multiple of 9. Squares under 225 are 196,169,144,121,100... 144 ie 12 squared (and 9 x 16) would seem to be the figure you're looking for.
Yes, yes, and no. 3- sum of digits must be multiple of 3. 6- sum of digits must be multiple of 3 and number must be even (multiple of 2). 9- sum of digits must be multiple of 9. (The sum of the digits here is 21.)
11 squared is 121
22
Yes If a numbers last two digits (assuming that it has at least two) is a multiple of 4, the whole number is also a multiple of 4. If the last two digits are 00 (assuming in this case it has at least three digits), the number is also a multiple of 4. For example, 100 and 200 are multiples of 4.