60 to 30 _ -1/2
30 to 20 _ -1/3
20 to 15 _ -1/4
15 to 12 _ -1/5
12 - (12*1/6) = 10
11
4 15 224 50175 By squaring the previous number minus one
75
twenty five
There are 15 government departments in Ireland. See the related link below for details.
In 1 day 10 men do 1/15 of the work and 15 women do 1/12, so in 1 day working together they would do 1/15 + 1/12 ie 9/60 or 3/20 so it would take 6 and two-thirds days.
The difference increases by one. 3, 6, 10, 15, 21, 28, 36 and so on.
12+12+15+15=54
23
number of composite numbers below 20: 10composite numbers below 20: 4, 6, 8, 9, 10, 12, 14, 15, 16, 18
15 degrees Celsius below 0 is -15 degrees Celsius.
23, 22, 44, 45. The pattern is minus 2, minus 1, times 2, plus 1, repeat.