# Practice Exercises for Number Theory

Directions: Read each question below. Click once in an ANSWER BOX and type in your answer; then click ENTER. Do not enter commas in your answers. After you click ENTER, a message will appear in the RESULTS BOX to indicate whether your answer is correct or incorrect. To start over, click CLEAR.

 1 Find the greatest common factor of 28 and 72. ANSWER BOX:  GCF =   RESULTS BOX:
 2 Find the least common multiple of 15 and 25. ANSWER BOX:  LCM =   RESULTS BOX:
 3 Name one prime number from 80 to 89. ANSWER BOX:   RESULTS BOX:
 4 The number 91 is composite. Name a number other than 1 and itself that is a factor of 91. ANSWER BOX:   RESULTS BOX:
 5 Which number is divisible by 3?  49, 87, 103, 119 ANSWER BOX:   RESULTS BOX:
 6 Which number is divisible by 8?  1821, 1496, 1246, 1586, 1634 ANSWER BOX:   RESULTS BOX:
 7 Write fourteen squared in standard form. ANSWER BOX:   RESULTS BOX:
 8 Write nine cubed in standard form. ANSWER BOX:   RESULTS BOX:
 9 The numbers 1, 8, 64, 512, ... are each powers of 8. What is the next number in the list?  ANSWER BOX:   RESULTS BOX:
 10 If five to the fourth power is 625, then what is five raised to the fifth power? ANSWER BOX:   RESULTS BOX: