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I have been given the number pattern 98, 72, 77, 49, 54, 20... How do I find the next two numbers?

First, let's look at the differences between the numbers in this pattern.

For example, if you subtract the second number (72) from the first number (98), you will get 26.

(First Term) - (Second Term) = 98 - 72 = 26
(Second Term) - (Third Term) = 72 - 77 = -5
(Third Term) - (Forth Term) = 77 - 49 = 28
(Forth Term) - (Fifth Term) = 49 - 54 = -5
(Fifth Term) - (Sixth Term) = 54 - 20 = 34

Now, the only pattern that seems obvious is that -5 is the result of every second calculation. If we continue this part of the pattern:

98 - 72 = 26
72 - 77 = -5
77 - 49 = 28
49 - 54 = -5
54 - 20 = 34
20 - ? = -5

So, the next number in the pattern should be 25.

Now, what explains the other numbers?

Take the first number (98). What connection is there between 98 and the next number in the pattern (72)? If you multiply the 9 and the 8 you get 72!

Now, the forth term (49) should also be created by multiplying the two digits in the previous term (77).
7 x 7 = 49.

To check this pattern - is the sixth term (20) created by multiplying the two digits of the fifth term (54)? Yes, 5 x 4 = 20

Can you see how this pattern works?