The number of dead zones in the ocean was around 50 in 1950. That number increased by a multiple of 10 by 2000. This rate is projected to continue if nothing is done. By 2100, how many dead zones would you expect there to be?

There is 45 different 2-digit numbers.

Step-by-step explanation:

My way is kinda dumb, but it still works. So, 2 digit numbers is from 10-99. We can start from the 10-19 first.

10, 11,12,13,14,15,16,17,18,19

We need to find the numbers that the tenth digit is greater than the units digit.

10, 11,12,13,14,15,16,17,18,19

Since 1 is the tenth digit, all the ones digits are all going to be bigger. Same goes with 20-29. Then you will have 2 numbers that the tenth digit is greater. My way applies when the tenth digit is only less than the ones digit, not greater. If you do this way...

10-19: 1 number

20-29: 2 numbers

30-39: 3 numbers

40-49: 4 numbers

50-59: 5 numbers

60-69: 6 numbers

70-79: 7 numbers

80-89: 8 numbers

90-99: 9 numbers

So, if you add 1+2+3+4++9(which all of you probably memorized by now) it would be 45. The answer is 45. Hope this helped!