Saudi Arabia's Foreign Exchange Reserves Surge 2.3% -- January 3, 2021

Link here. 

This is pretty cool. This increase was reported as 2.3% late last week and that turns out to be accurate: 2.314488%:

Back of the envelope:

• 1674841 million * 0.27 = $452.20707 billion
• 1713605 million *0.27 =  $462.67335 billion
• Delta, November over October: $10.46628 billion

Now, let's look at change in price of OPEC basket:

• October 20, 2020: $41 but by the end of the month had dropped to $39;
  
• November 15, 2020: $43 but by the end of the had jumped to $46
  

$2/bbl * 210 million bbls = $420 million. 

$7/bbl * 210 million bbls = $1.47 billion