def hitungNomorBit (angka, nomorBit):
	# validasi input
	if angka < 0 or nomorBit < 0:
		return None
 
	# konversi angka desimal ke biner
	biner = []
	while angka > 0:
		biner.insert(0, angka % 2)
		angka = angka // 2
 
	# jika nomor bit melebihi panjang biner, kembalikan none
	if nomorBit >= len(biner) or biner[nomorBit] == 0:
		return None
 
	# hitung jumlah keseluruhan bit di posisi nomorBit
	jumlah = 0
	for i in range(0, nomorBit + 1):
		if biner[i] == 1:
			jumlah += 2 ** (i)
 
	return jumlah
 
print(hitungNomorBit(13, 3))

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