Ok so 2 dice the probability means (desired outcomes)/(total possible outcomes)
one way is to list all outcomes and find the desirable ones (I will list and find product and bold all numbers less than 13) product of 2 numbers means multiply fyi
If you consider "3-digit" numbers to be between 100 and 999, inclusive, there are 128 such numbers divisible by 7. The probability of choosing one at random is ...
128/900 = 32/225 = 0.1422...(repeating)
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If you consider all non-negative integers less than 1000 to be "3-digit numbers," then the probability is ...