Molly started her Novemeber "Read-a Lot" money raising progamme on the first day of the month, at the top of page 63 of her very large book. She read 23 pages the first day, 30 pages the second, then 37 pages on November 3. She continued, reading 7 pages extra each day, until the end of the month. On what page did she finish?
Misread the question at first...
This is an arithmetic sequence to which the total is added to 63
Sn = n(a1+an)/2
an = a30 = a1+(n-1)d = 23 + 29(7) = 226
Sn= 30(23+226)/2 +63= page 3798