0 = zero 1 = one 2 = two 3 = three 4 = four 5 = five 6 = six 7 = seven 8 = eight 9 = nine 10 = ten 11 = eleven 12 = twelve 13 = thirteen 14 = fourteen 15 = fifteen 16 = sixteen 17 = seventeen 18 = eighteen 19 = nineteen 20 = twenty 21 = twenty one 98 = ninety eight 99 = ninety nine 100 = one hundred 101 = one hundred one 102 = one hundred two 900 = nine hundred 901 = nine hundred one 999 = nine hundred ninety nine 999,999,999,999,999 = nine hundred ninety nine trillion nine hundred ninety nine billion nine hundred ninety nine million nine hundred ninety nine thousand nine hundred ninety nine 1,000,000,000,000,000 = Sorry, can't handle numbers with more than 15 digits