test {
    test {
        "a*b=X"
        a = [0..9]
        b = [0..9] * [10]
        ~
        "x/a=B"
        ~
        "x/b=A"
    }
}

addition {
    level1 {
        "A+b=x" "a+B=x"
        a = [0..9]
        b = [0..9]
        x == 10
    }
    level2 {
        "a+b=X" "A+b=x" "a+B=x"
        a = [0..20]
        b = [0..20]
        x <= 20
    }
    level3 {
        "A+b=x" "a+B=x" "a+b=X"
        m = ~[1, 10]
        a = [0..10] * m
        b = [0..10] * m
        x < 100
    }
    level4 {
        "A+b=x" "a+B=x" "a+b=X"
        a = [0..100]
        b = [0..100]
        x < 100
    }
    level5 {
        "A+b=x" "a+B=x" "a+b=X"
        a = [0..100]
        b = [0..100]
        x < 100
    }
    level9 {
        "A+b=x" "a+B=x" "a+b=X"
        a = [0..100]
        b = [0..100]
        x < 100
    }
}

subtraction {
    level1 {
        "A-b=x" "a-b=X"
        a = [0..10]
        b = [0..10]
        x >= 0
    }
}

division {
    level1 {
        "b/a=X"
        a = [1, 2, 5, 10]
        b = a * [4,8,0]
    }
    level2 {
        "b/a=X"
        a = [1, 2, 5, 10]
        b = a * [3,6,9]
    }
    level3 {
        "b/a=X"
        a = [1, 2, 5, 10]
        b = a * [7]
    }
    level5 {
        "b/a=X"
        a = [1, 2, 5, 10]
        b = a * [0..9]
    }
    level5 {
        "B/a=x" "b/A=x"
        a = [1, 2, 5, 10]
        b = a * [0..9]
    }
}

multiplication {
    level1 {
        "a*b=X" "b*a=X"
        a = [1, 2, 5, 10]
        b = [0..10]
        x <= 100
    }
    level1 {
        "a*b=X" "b*a=X"
        a = [1, 2, 5, 10]
        b = [0..10]
        x <= 100
    }
    level2 {
        "a*b=X" "b*a=X"
        a = [4, 8, 0]
        b = [0..10]
        x <= 100
    }
    level3 {
        "a*b=X" "b*a=X"
        a = [3, 6, 9]
        b = [0..10]
        x <= 100
    }
    level4 {
        "a*b=X" "b*a=X"
        a = [7]
        b = [0..10]
        x <= 100
    }
    level5 {
        "a*b=X" "b*a=X"
        a = [0..10]
        b = [0..10]
        x <= 100
    }
    level6 {
        "A*b=x" "a*B=x"
        a = [0..10]
        b = [0..10]
        x <= 100
    }
    level {
        "a*b=X" "b*a=X"
        a = [1..99]
        b = [10, 100]
        x <= 1000
    }
    level7 {
        "a*b=X"
        a = [1, 10] * [0..9]
        b = [1, 10] * [0..9]
        x <= 1000
    }
    level8 {
        "A*b=x" "a*B=x"
        a = [1, 10] * [0..9]
        b = [1, 10] * [0..9]
        x <= 1000
    }
    level9 {
        "a*b=X"
        a = [11, 12]
        b = [2..10]
        x <= 100
    }
    level10 {
        "a*b=X"
        a = [10, 100, 1000] * [2..9]
        b = [10, 100, 1000] * [2..9]
        x <= 1000000
    }
    level {
        "A*b=x" "a*B=x"
        a = [1..9] * [10, 100, 1000]
        b = [1..9] * [10, 100, 1000]
        x <= 1000000
    }
}