(64 = 4 × 4 × 4). 8 has four factors ... 3 + 13 = 16 and 5 + 11 = 16. Draw a factor tree close. Write the number and draw two branches to give a factor pair, both greater than 1.

A prime number has exactly two factors, itself and one. The first ten prime numbers are \({2}\), \({3}\), \({5}\), \({7}\), \({11}\), \({13}\), \({17}\), \({19 ...