В «Занимательной арифметике» известного популяризатора наук Якова Исидоровича Перельмана в конце первой главы я нашел пример следующих «Арифметических курьезов»:
(+, -)
100 = 1+2+3+4+5+6+7+8*9
100 = 12+3-4+5+67+8+9
100 = 12-3-4+5-6+7+89
100 = 123+4-5+67-89
100 = 123-45-67+89
усложняем задачу (+, -, *, /)

123+45-67+8-9 = 100
123+4-5+67-89 = 100
123+4*5-6*7+8-9 = 100
123-45-67+89 = 100
123-4-5-6-7+8-9 = 100
12+34+5*6+7+8+9 = 100
12+34-5+6*7+8+9 = 100
12+34-5-6+7*8+9 = 100
12+34-5-6-7+8*9 = 100
12+3+4+5-6-7+89 = 100
12+3+4-56/7+89 = 100
12+3-4+5+67+8+9 = 100
12+3*45+6*7-89 = 100
12+3*4+5+6+7*8+9 = 100
12+3*4+5+6-7+8*9 = 100
12+3*4-5-6+78+9 = 100
12-3+4*5+6+7*8+9 = 100
12-3+4*5+6-7+8*9 = 100
12-3-4+5-6+7+89 = 100
12-3-4+5*6+7*8+9 = 100
12-3-4+5*6-7+8*9 = 100
12*3-4+5-6+78-9 = 100
12*3-4-5-6+7+8*9 = 100
12*3-4*5+67+8+9 = 100
12/3+4*5-6-7+89 = 100
12/3+4*5*6-7-8-9 = 100
12/3+4*5*6*7/8-9 = 100
12/3/4+5*6+78-9 = 100
1+234-56-7-8*9 = 100
1+234*5*6/78+9 = 100
1+234*5/6-7-89 = 100
1+23-4+56+7+8+9 = 100
1+23-4+56/7+8*9 = 100
1+23-4+5+6+78-9 = 100
1+23-4-5+6+7+8*9 = 100
1+23*4+56/7+8-9 = 100
1+23*4+5-6+7-8+9 = 100
1+23*4-5+6+7+8-9 = 100
1+2+34-5+67-8+9 = 100
1+2+34*5+6-7-8*9 = 100
1+2+3+4+5+6+7+8*9 = 100
1+2+3-45+67+8*9 = 100
1+2+3-4+5+6+78+9 = 100
1+2+3-4*5+6*7+8*9 = 100
1+2+3*4-5-6+7+89 = 100
1+2+3*4*56/7-8+9 = 100
1+2+3*4*5/6+78+9 = 100
1+2-3*4+5*6+7+8*9 = 100
1+2-3*4-5+6*7+8*9 = 100
1+2*34-56+78+9 = 100
1+2*3+4+5+67+8+9 = 100
1+2*3+4*5-6+7+8*9 = 100
1+2*3-4+56/7+89 = 100
1+2*3-4-5+6+7+89 = 100
1+2*3*4*5/6+7+8*9 = 100
1-23+4*5+6+7+89 = 100
1-23-4+5*6+7+89 = 100
1-23-4-5+6*7+89 = 100
1-2+3+45+6+7*8-9 = 100
1-2+3*4+5+67+8+9 = 100
1-2+3*4*5+6*7+8-9 = 100
1-2+3*4*5-6+7*8-9 = 100
1-2-34+56+7+8*9 = 100
1-2-3+45+6*7+8+9 = 100
1-2-3+45-6+7*8+9 = 100
1-2-3+45-6-7+8*9 = 100
1-2-3+4*56/7+8*9 = 100
1-2-3+4*5+67+8+9 = 100
1-2*3+4*5+6+7+8*9 = 100
1-2*3-4+5*6+7+8*9 = 100
1-2*3-4-5+6*7+8*9 = 100
1*234+5-67-8*9 = 100
1*23+4+56/7*8+9 = 100
1*23+4+5+67-8+9 = 100
1*23-4+5-6-7+89 = 100
1*23-4-56/7+89 = 100
1*23*4-56/7/8+9 = 100
1*2+34+56+7-8+9 = 100
1*2+34+5+6*7+8+9 = 100
1*2+34+5-6+7*8+9 = 100
1*2+34+5-6-7+8*9 = 100
1*2+34-56/7+8*9 = 100
1*2+3+45+67-8-9 = 100
1*2+3+4*5+6+78-9 = 100
1*2+3-4+5*6+78-9 = 100
1*2+3*4+5-6+78+9 = 100
1*2-3+4+56/7+89 = 100
1*2-3+4-5+6+7+89 = 100
1*2-3+4*5-6+78+9 = 100
1*2*34+56-7-8-9 = 100
1*2*3+4+5+6+7+8*9 = 100
1*2*3-45+67+8*9 = 100
1*2*3-4+5+6+78+9 = 100
1*2*3-4*5+6*7+8*9 = 100
1*2*3*4+5+6+7*8+9 = 100
1*2*3*4+5+6-7+8*9 = 100
1*2*3*4-5-6+78+9 = 100
1*2/3+4*5/6+7+89 = 100
1/2*34-5+6-7+89 = 100
1/2*3/4*56+7+8*9 = 100
1/2/3*456+7+8+9 = 100
via