If you are 20 years old, you have been alive for about 630 , 000 , 000 seconds. write this number in scientific notation.

6.3 * 10^8

To get this answer, you write the decimal point between the first two nonzero digits, which are 6 and 3. Then you need to count how many spaces it takes to move the decimal point so that it gets back to where it originally was, which was after the long string of 0's. You should count out 8 spaces, so the exponent over the "10" is going to be 8. The exponent 8 says "move the decimal point 8 spots to the right. The positive exponent means "move right"

35-60 students are taking math.

if gloria has "carry over" minutes, (that is, any minutes paid for but not used in a month can be applied to her payment for minutes in the next month,) her total usage for the three months is: total minutes = 320 + 243 + 489 = 1052 minutes number of 200 minute blocks = 1052/200 = 5 r52 (that is 5 with a remainder of 52) rounding up the number of 200 minute blocks gives her usage for the three months as 6 blocks. the cost for six blocks is 6 x $25 = $150 she also has 200 - 52 or 148 carry over minutes if gloria pays each month and unused minutes are lost, applying the rounding up procedure to each month gives: first month usage of 320 minutes rounds up to 2 blocks of 200 minutes for a payment of 2 x $25 = $50 second month usage of 243 minutes rounds up to 2 blocks of 200 minutes for a payment of 2 x $25 = $50 third month usage of 489 minutes rounds up to 3 blocks of 200 minutes for a payment of 3 x $25 = $75 total payments for the three months are $50 + $50 + $75 = $175 get the plan with carry over minutes!