DouKaku?

def calc( x, ho ){
    x = x.replaceAll(/[0-9]+/, {
        def num = it.toInteger()

        seikika( num, ho ).toString()
    })
    seikika(new Eval().me(x), ho)
}

def seikika( num, ho ){
    while(num < 0 ){
        num += ho
    }
    num % ho
}

println calc("10 + 35", 10)
println calc("2 * 3", 10)
println calc("11 * 12", 10)
println calc("18 * 39", 10)

println calc("-13 * 11",7)
println calc("7 * 9",7)
println calc("3 * 4",7)