각 4 개의 방정식:
111-11 = 100,1111-1 = 1110,111-1-1 = 109,11-1-1-1 = 8
222-22 = 200,2222-2 = 2220,222-2-2 = 218,22-2-2-2 = 16
333-33 = 300,3333-3 = 3330,333-3-3 = 327,33-3-3-3 = 24
444-44 = 400,4444-4 = 4440,444-4-4 = 436,44-4-4-4 = 32
555-55 = 500,5555-5 = 5550,555-5-5 = 545,55-5-5 = 40
666-66 = 600,6666-6 = 6660,666-6-6 = 654,66-6-6-6 = 48
777-77 = 700,7777-7 = 7770,777-7-7 = 763,77-7-7-7 = 56
888-88 = 800,8888-8 = 8880,888-8-8 = 872,88-8-8-8 = 64
999-99 = 900,9999-9 = 9990,999-9-9 = 981,99-9-9-9 = 72