Shadowfax13

3 + 4 + 5 = 12 could work. It's probably not the smallest.

Take a look at https://web2.0calc.com/questions/the-probability-of-snow-for-each-of-the-next-three-days-is-frac-3-4-what-is-the-probability-that-it-will-not-snow-at-all-during-the-ne . It's very similar. If you still can't solve it, ask here.

I got 11 :D

7 cartons full of large boxes, and 4 cartons full of small boxes.

56 + 40 = 96, and so we have 11 cartons.

Please explain more clearly, but here is what I interpret it as.

10^x times 10^-9 = 10^11

So, how are we going to do this?

If you know exponents well, if you multiply exponents, say, 10^5 times 10^6, the answer is 10^11. How to get that? The base (10) is the same, so we are allowed to add the exponent powers for the answer. Thus, using the same logic, what plus -9 is 11? We have x = 20 with this.

Hope this helps.

Like Guest said, there are 999 - 100 + 1 = 900 numbers between 100 and 999 inclusive.

Now, think about it. The hundreds. Let's tackle 100. 107, 117, 127, 137, 147, 157, 167, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 187, and 197. How many numbers is that? Counting, it is a list of 19 numbers. 19 x 9 = 171. Why is it times 9, not 10? Well, we gotta skip the 700s because there is a 7 in all of them. In 700 - 799, there are 100 numbers with a 7 in it. 100 + 171 = 271. Therefore, 900 - 271 = 629 numbers 100 - 999 which can be written without 7's.