Answer:
12
Step-by-step explanation:
There are 4 different digits to choose from. Since we want 2-digit number, we will see what digits can we put in place of 1st digit and what digit can we place in place of 2nd digit.
Hence, <u><em>how many digits (from 1,5,6 and 8) can be placed in the 1st digit of the number we want?</em></u>
Any one of the four digits (1,5,6, or 8).
Now, <em><u>How many digits (from 1,5,6 and 8) can be placed as the 2nd digit of the number we want?</u></em>
Any one of the THREE digits (since repetition is not allowed, we disregard the initial digit).
Thus the number of two-digit positive integers is 4 * 3 = 12
A. multiplication is your answer.
Let the legs of the triangle be a and b, and the hypotenuse c.
Your first instinct might tell you to use the Pythagorean theorem to go about solving this because

. This works, but it is slow.
The fastest way to solve this is to recognize that the right triangle is a special triangle where the ratio of the sides are 3:4:5. This means that if the legs are 9 and 12, then the hypotenuse is 15 because 3*3 is 9, 3*4 is 12, and 3*5 is 15.
210:1260
If simplified it is
1:6
If Hope this helped if any question feel free to ask!! :D
Counting each visible cube, and multiplying it by 2, he used 112. If you counted them, there would be 56 cubes. You'd multiply by 2 for the non-visible ones.