Practice Ciphering Round 1

Front

What is the rule for a number to be divisible by 3?

Back

A number is divisible by 3 if the sum of its digits is divisible by 3.

Front

In the number 3A6,792, what is the maximum value of A for divisibility by 3?

Back

The maximum value of A is 9, making the sum of the digits 36, which is divisible by 3.

Front

What are factors of a number?

Back

Factors are numbers that can be multiplied together to get the original number.

Front

How do you find the number of factors of a number?

Back

To find the number of factors, determine the prime factorization of the number and use the formula: (e1+1)(e2+1)...(en+1), where e1, e2,..., en are the exponents in the prime factorization.

Front

What is the prime factorization of 40?

Back

The prime factorization of 40 is 2^3 * 5^1.

Front

How many total factors does 40 have?

Back

40 has 8 factors: 1, 2, 4, 5, 8, 10, 20, and 40.

Front

What is a rate in mathematics?

Back

A rate is a ratio that compares two quantities with different units.

Front

If 90 cards can be copied in 30 minutes, what is the rate of copying cards per minute?

Back

The rate is 3 cards per minute (90 cards / 30 minutes).

Front

How do you calculate the time needed to complete a task at a constant rate?

Back

Time = Total Work / Rate.

Front

If it takes 30 minutes to copy 90 cards, how long will it take to copy 540 cards?

Back

It will take 3 hours to copy 540 cards.