Sure!
I multiply each value by 4, since a float32 takes 4 Bytes (4*8=32). So if you are dealing with 70,000 float32 values, you should allocate 70,000*4 = 280,000 Bytes. To convert Bytes to GB, you would have to divide it three times by 1024, which is where the / 1024**3 comes from.