Subnetting is easy

With this little table subnetting is a piece of cake

Select either subnet or CIDER to get other one
Divide octet number of last host, multiply by whole numbers from division = The start of the range
Addon a group for next range
Minus -1 from next range for range end
Broadcast is last IP in range
2 power of Number of host bit = number of hosts, in first octet look at group size or 32 - CIDR =x hen 2^x = number of host address - 2 for usable

example
192.168.45.56 /24
192.168.45.56 255.255.255.0

It is in octet 3 so first octet is 0 as it is all host ips
45 / 1 = 45 > 45 * 1 = 45 therefore 192.168.45.0 is start of range
add a group to get the next = 192.168.46.0
broadcast address subtract 1 192.168.45.255
Number of address = 32-24=8 2^8=256 (because group is in 3 octet)

or you can use a calculator
https://www.calculator.net/ip-subnet-calculator.html

example in 2nd octet 10.32.1.20 /12
/12 relates to group size 16
32/16 = 2
16 * 2 = 32
ip address start = 10.32.0.0 255.240.0.0
range 10.32.0.0 - 10.48.0.0 (add on group)
Broadcast = 10.47.255.255
Number of Ips = 32 - 12 = 20, 2^20=1 048 576