struct MyBigInt
    sign::Symbol
    base::Int
    digits::Vector{Int64}
end

p1 = MyBigInt(:+, 1000, Vector([1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0]))

MyBigInt(:+, 1000, [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0])

Figure 1: ?(caption)

# example value in Julia's Base.BigInt
n::BigInt = 1234567890 

# some functions to test my implementation
function to_base_big(n::MyBigInt)
    ret::BigInt = 0
    for i in 1:length(n.digits)
        ret += BigInt(n.digits[i]) * n.base ^ (i - 1) 
    end
    return ret
end

function from_base_big(n::BigInt; base::Int64 = 1000)
    ret::MyBigInt = MyBigInt(:+, base, [])
    while n > 0
        push!(ret.digits, mod(n, ret.base))
        n = div(n, ret.base)
    end
    return ret
end

# round trip test
to_base_big(from_base_big(n))

1234567890

Figure 2: ?(caption)

1234567890

div(n, 1000)

1234567

1234567890

from_base_big(n)

MyBigInt(:+, 1000, [890, 567, 234, 1])

ret::BigInt = 0
for i in 1:length(n.digits)
    ret += BigInt(n.digits[end - i]) * n.base * (i - 1) 
end

ErrorException: type BigInt has no field digits

for i in 10:-1:1
    println(i)
end

10
9
8
7
6
5
4
3
2
1