如何将数字格式化为字符串(1k，2M...)而不是在python中四舍五入？

def format_number(num):
    units = ['', 'k', 'M', 'G', 'T']
    unit_index = 0
    while abs(num) >= 1000 and unit_index < len(units)-1:
        num /= 1000
        unit_index += 1
    return '%.2f%s' % (num, units[unit_index])

num = 1234567
formatted_str = format_number(num)
print(formatted_str)  # 输出：1234.57k

def format_number(num):
    units = ['', 'k', 'M', 'G', 'T']
    unit_index = 0
    while abs(num) >= 1000 and unit_index < len(units)-1:
        num /= 1000
        unit_index += 1
    return '{:.2f}{}'.format(num, units[unit_index])

num = 1234567
formatted_str = format_number(num)
print(formatted_str)  # 输出：1234.57k