How to make calculations using Decimal to Hex converter?

Help me understand this article ECDSA Signature and the “z” valueI have questions on the calculation of these formulas? I use to calculate MATLAB all the values ​​I converted via (Decimal to Hex converter)

I received everything as well as it is written m1-m2 = 0xA931DC8C0E011326AE4D6FAB7DED290B196966154E0A73A0DF434413217B3E92 m1-m2 = 76528969076809802026489893831367609005958270788084878882377179170733928693394 ~~~~~~~~~~~~~~~~~~~~

s1-s2 = 0xAA82E2B8191F2B00C8788571CC8BEA41086440225A4B5CBED84D02CF638123D4 s1-s2 = 77124439135526666464729219906693069544254583044290140925196448240593790903252 ~~~~~~~~~~~~~~~~~~~~

But when I reached the secret meaning of "k" I did not get this value 0x7a1a7e52797fc8caaa435d2a4dace39158504bf204fbe19f14dbb427faee50ae

How to calculate by this formula Using (Decimal to Hex converter ?? m1-m2) / (s1-s2) = 0x7a1a7e52797fc8caaa435d2a4dace39158504bf204fbe19f14dbb427faee50ae

And more a question how to receive modulare inverse of s1-s2 = 0xf7d5417b3844fd8f4b3d909979fa7480ce094fb233d759274fd6c3aa6cf86593