It took my almost 20 minutes to get all the answers
(1). 7, 9 , 11, 13 ,15 , 17, 19.
(2). 5, 10 , 15, 20 , 25 , 30, 35, 40.
(3). 500, 600, 700, 800, 900, 1000, 1100 , 1200.
(4). 25, 50, 75, 100 , 125, 150 , 175.
(5). 53, 65, 77, 89, 101, 113, 125 , 137.
(6). b, d, f, h , j, l, n, p.
(7). c, g, k, o, s.
(8). 15, 14, 13, 12, 11, 10, 9, 8.
(9). 30, 27, 24, 21, 18, 15, 12.
(10). 125, 120, 115, 110, 105, 100, 95, 90.
(11). 1100, 1075, 1050, 1025,1000, 975, 950, 925.
(12). x, w, v, u, t, s, r.
(13). q, o, m, k, i, g, e, c.
(14). y, v, s, p, m, j, g, d.
(15). 8, 2, 8, 8, 2, 8, 8, 8, 2, 8, 8, 8, 8, 2, 8, 8, 8, 8, 8.
(16). 6, 77, 888, 9999, 1010101010, 111111111111, 12121212121212.
(17). 2, 23, 234, 2345, 23456, 234567.
(18). 1, 31, 531, 7531, 97531, 1197531, 131197531.
(19). 11, 99, 22, 88, 33, 77, 44, 66, 55, 55, 66, 44.
(20). 3, 18, 6, 16, 9, 14, 12, 12, 14, 10, 16.
(21). 6, 24, 12, 24, 18, 24, 24, 24, 30, 24.
(22). 5, 6, 7, 9, 9, 12, 11, 15, 13, 18, 15.
(23). 10, 50, 15, 40, 20, 30, 25, 20, 30, 10.
(24). p, q, o, r, n, s, m, t, l, u.
(25). Z, N, X, O, V, P, T, Q, R, R, P.