70 MPH on motorway converts as 112Km/Hr, but rounded up to 120Km/Hr.
60MPH was the limit for most roads converts as 96Km/Hr, but has been converted to 100Km/Hr.
The access road to Mountjoy Prison apparently had a speed limit of 10miles/hour, but the officials seemingly could not agree on a rounding policy - and so we ended up with a, possibly unique, limit of 16 Km/Hr.