User: HOW TO CALCULATE THE NUMBER OF VARIATIONS IN A 4-DIGIT NUMBER

Weegy: Start by writing down all the possibilities for the first digit. They are 0 1 2 Use each of these as a base for a two digit number. [ From each of the one digit numbers you can construct 3, two digit number, they are 00 01 02 10 11 12 20 21 22 Hence there are 3 3 = 9, two digit numbers. Use each of these as a base for a three digit number. From each of the two digit numbers you can construct 3, three digit number, they are 000 001 002 010 011 012 020 021 022 100 101 102 110 111 112 120 121 122 200 201 202 210 211 212 220 221 222 Hence there are 3 3 3 = 27, three digit numbers. Use each of these as a base for a four digit number. From each of the three digit numbers you can construct 3, four digit number. there are 3 3 3 3 = 81, four digit numbers. ]
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