Counting Principles Flashcards

All 4 cards in this deck

What does it mean to list possibilities systematically?

Writing them in a fixed order (e.g. smallest first) so none are missed or repeated.

How do you count the number of combinations when choosing one item from each of two lists?

e.g. 3 starters and 4 main courses

Multiply the numbers in the lists: $3 \times 4 = 12$ combinations.

How do you make the largest possible 3-digit number from a set of digits?

e.g. from 7, 3, 4, 9

Put the largest digits first, in decreasing order: $974$.

True or false? Using the digits 0, 3 and 7, '03' counts as one of the two-digit numbers.

False. A two-digit number cannot start with 0.